Mechatronics Systems Engineering - Theses, Dissertations, and other Required Graduate Degree Essays

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Empirical Modeling of Fuel Cell Durability: Cathode Catalyst Layer Degradation

Author: 
Date created: 
2017-12-06
Abstract: 

Fuel cells for automotive applications do not yet match the durability and cost of conventional engines. Durability can be improved by better understanding degradation mechanisms of fuel cell components. A critical component is the cathode electrode, which facilitates the slow oxygen reduction reaction. In this work, fuel cells with state of the art electrodes are manufactured and subjected to degradation tests simulating two drive cycle conditions: load cycling, and start-up/shutdown cycling. The degradation data is used to empirically model the voltage loss due to cathode electrode degradation, to predict voltage loss throughout fuel cell lifetime, and compare to findings in literature. The model may be used as a starting point to better understand electrode degradation, and to develop fundamental models. Based on degradation results it is recommended to investigate coupling effects between the different drive cycle conditions, impact of mitigation factors, and effect of different catalyst loadings on the electrode durability.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Erik Kjeang
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Thermal performance of aerogel blanket insulation

Author: 
Date created: 
2017-09-08
Abstract: 

Population growth has significantly increased the energy consumption of the building sector, which is currently 32% of the total global energy demand. Energy use for residential and commercial heating and cooling is projected to strongly grow until 2050, increasing by 79% and 84%, respectively, compared to 2010 [1]. Development of high performance thermal insulation materials is crucial to saving space and energy, increasing comfort, and decreasing environmental impact, cost, and complexity. Aerogels are a promising high-performance type of thermal insulation for both stationary and mobile applications. The thermal performance of insulations is typically judged by their reported R-value (thermal resistance); however, this value may differ from the in-service R-value for reasons such as temperature and humidity variations as well as mechanical compression.In this research, the thermal performance of aerogel blanket super insulation is thoroughly studied under various operating conditions, i.e., temperature, compression, and humidity. The microstructure of commercially available aerogel blankets was characterized using microscopy, porosimetry and spectroscopy. A comprehensive set of accurate analytical models were developed and verified experimentally to predict the thermal and mechanical performance of aerogel blankets in dry and humid conditions. These models can be utilized to predict the thermal performance of the insulation for building envelopes and other large-scale applications. Furthermore, the design of such materials can be improved by performing an optimization study on the microstructural and morphological properties of aerogel blankets using the developed analytical models.The results of the aerogel blanket performance modeling and measurements indicated that mechanical load on the material, elevated temperature and high humidity decrease the R-value of aerogel blankets. These factors should be considered in the thermal insulation design and selection for an application to benefit the most from this super insulation material.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Majid Bahrami
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Consolidated composite adsorbent containing graphite flake for sorption cooling systems

Date created: 
2017-07-06
Abstract: 

Heat-driven sorption technology, as a sustainable and clean solution for thermal management and heat storage, has drawn a significant interest in academic and industrial research community. This interest has been intensified in the last decade as environmental and climate changes issues are becoming major global challenges. Numerous studies aim to improve materials sorption performances, as it is at the core of sorption cooling or storage systems. Due to the nature of the sorption process, heat and transport properties, e.g., thermal diffusivity and thermal conductivity of the adsorbent material play an important role in their performance. Higher thermal diffusivity can enhance the heat transfer rate and lead to faster sorption/desorption cycles and more efficient (more compact) heat-driven sorption chillers. A key part of the sorption chillers design is developing adsorbent materials (or composites) with superior hydrophilicity, high water uptake capacity, low regeneration temperature (60-150°C), and high thermal diffusivity. The focus of this research is to design tailored consolidated composite adsorbent containing graphite flakes with improved heat and mass transfer properties for sorption cooling systems. The presented Ph.D. dissertation is divided into three main parts: (i) composite adsorbent fabrication and characterization; (ii) consolidated composite characterization; and (iii) thermal properties modeling of consolidated composite adsorbent. Fabricated loose grain and consolidated composite were characterized in Dr. Bahrami’s Laboratory for Alternative Energy Conversion (LAEC) and SFU 4D LABS.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Majid Bahrami
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Plate Heat Exchangers Using Natural Graphite Sheets

Author: 
Date created: 
2017-07-31
Abstract: 

Graphite heat exchangers (G-HEX) are good alternatives to metallic heat exchangers due to their excellent thermal properties, low cost, light weight, and high resistivity to corrosion. In this study, the potential of fabrication of natural flake graphite-based plate heat exchanger is being investigated. A new layered G-HEX and a graphite plate heat exchanger are fabricated and their thermal and hydraulic performance are compared with an off-the-shelf chevron-type plate heat exchanger using a custom-made experimental setup. An optimization study is then conducted to further improve the graphite plate heat exchanger performance. To understand the potential of utilization of G-HEX in corrosive environments, a corrosion test is then performed on natural flake graphite sheets.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Majid Bahrami
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Electrical impedance and diffuse optical spectroscopy for early breast cancer diagnosis

Author: 
Date created: 
2017-08-16
Abstract: 

In this thesis, we apply sensor-based tools for investigating breast tissue characteristics to identify anomalies, including cancer. The non-invasive technologies utilized are based on the Electrical Impedance Spectroscopy (EIS) and Diffuse Optical Imaging (DOI). As the accuracy of Clinical Breast Examination (CBE) depends on the physician’s experience, these technologies enhance the diagnostic capabilities by providing additional information. We tested twenty patients utilizing these technologies, in a clinical trial, with around 100% success rate in identifying the location of cancerous tumors.The correlation between healthy and cancerous tissue electrical properties is defined by extracting the electrical features of tissues based on Cole-Cole model. Also, by processing the raw data of the DOI-probe, we have been able to create the cross-sectional optical images of the breast in different wavelengths from 690nm to 850nm. This study suggests that EIS and DOI are useful technologies for early detection of breast cancers.

Document type: 
Thesis
Supervisor(s): 
Dr. Farid Golnaraghi
dr. Carolyn Sparrey
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Modelling the stability and maneuverability of a manual wheelchair with adjustable seating

Date created: 
2017-08-17
Abstract: 

Manual wheelchairs are generally designed with a fixed frame, which is not optimal for every situation. Spontaneous changes in seating configuration can ease transfers, increase participation in social activities, and extend reaching capabilities. These changes also shift the centre of gravity of the system, altering wheelchair dynamics. In this study, rigid body models of an adjustable manual wheelchair and test dummy were created to characterize changes to wheelchair stability and maneuverability for variations in backrest angle, seat angle, rear wheel position, user position, and user mass. Static stability was evaluated by the tip angle of the wheelchair on an adjustable slope, with maneuverability indicated by the ratio of weight on the rear wheels. Dynamic stability was assessed for the wheelchair rolling down an incline with a small bump. Both static and dynamic simulations were validated experimentally using motion capture of real wheelchair tips and falls. Overall, rear wheel position was the most influential wheelchair configuration parameter. Adjustments to the seat and backrest also had a significant impact on both static and dynamic stability. For wheelchairs with a more maneuverable (or 'tippy') initial configuration, dynamic seating changes could be used to increase stability as required.

Document type: 
Thesis
File(s): 
Example comparison of experimental and simulation dynamic stability trials
Supervisor(s): 
Carolyn Sparrey
Jaimie Borisoff
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Energy Management Strategies and Evaluation for Plug-in Electric Vehicles - On and Off the Road

Author: 
Date created: 
2017-08-28
Abstract: 

Electric vehicle (EV) industries are driven by new technologies in batteries and powertrains. This thesis studies the cutting-edge Formula E racing vehicles with vehicle simulation and optimization for energy efficiency. On the consumer side, a new challenge EVs introduce is the need for large-scale charging infrastructure with minimum grid impact. This thesis studies EV charging management on the daily basis, featuring practical smart charging solutions at public locations and bi-directional (dis)charging at workplace and residence. Techniques that support smart charging are also studied. A data-mining based load disaggregation approach is developed to evaluate the general energy usage in the residential context. A machine-learning based load forecasting model is proposed to predict short-term residential loads in ultra-small scales. Overall, this thesis anticipates every aspect of EVs' daily activities, whether it is on or off the road, and suggests solutions to maximizing EV utilization for both drivers and the smart grid.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Gary Wang
Hassan Farhangi, Ali Palizban
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Modeling and Control of the Fuel Supply System in a Polymer Electrolyte Membrane Fuel Cell

Date created: 
2017-05-30
Abstract: 

Prolonging membrane longevity as well as improving fuel economy are essential steps toward utilization of fuel cells in industrial applications. Focusing on polymer electrolyte membrane (PEM) fuel cells, the present work elucidates a systematic approach to deal with cell durability issues, inflicted by membrane pinholes. This includes the model-based control of fuel overpressure, which is defined as the pressure difference between the anode and cathode compartments, at the inlet side of the fuel cell stack. Moreover, to enhance fuel savings, this work proposes a novel model-based technique for estimation of hydrogen concentration, which is used as the basis of fuel purging control. Employing a Ballard 3kW test station equipped with a 9-cell Mk1100 PEM fuel cell, the entire system is modeled using pneumatic variables. The developed model is experimentally validated. Depending on the underlying objective, a relevant system configuration for the PEM fuel cell anode is adopted. These include a flow-through anode, dead-ended anode, and anode with recirculation structures. A model predictive controller (MPC) is deployed to achieve the controller objectives, which include the improvement in control of the system transient response during the load change, reduction of hydrogen emission, and retaining the cell voltage level of a defective cell, by maintaining the fuel overpressure in the desired region. Furthermore, the controller performance is verified experimentally. Using the pressure drop across the fuel cell stack anode, the hydrogen concentration on the anode side is estimated in a hydrogen-nitrogen gas mixture. This pressure drop is correlated to the dynamic viscosity of a gas mixture. The estimation model which is verified experimentally for various scenarios provides a reliable and cost-effective method that can eliminate the use of the hydrogen sensor. This model is then utilized as the basis for controlling the fuel purging. Deploying an MPC based multivariable control strategy, both fuel overpressure and hydrogen concentration are controlled.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Farid Golnaraghi
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

A Fully 3D-printed Integrated Electrochemical Sensor System

Author: 
Date created: 
2017-08-30
Abstract: 

This thesis investigates the design, fabrication, and characterization of a 3D printed electrochemical sensor as well as compact potentiostat circuits on Printed Circuit Board (PCB) for portable electrochemical sensing applications. Conductive 3D printing technologies are investigated as well as the advances in sensors and electronics applications. An optimized Directly Ink Writing (DIW) technique is adapted to a novel 3D-PCB fabrication platform using silver nanoparticle ink for electronics applications. An electrochemical device called potentiostat is designed based on an open source system. Its prototype is 3D printed on FR4 substrate. Using the same 3D platform, a lactate sensor which is composed of a 3-electrode is printed on the flexible substrate. Together, the 3D printed system demonstrates the electrochemistry test including cyclic voltammetry (CV) and amperometry. Results of this research demonstrate that 3D-PCB technology can significantly accelerate the fabrication process of conventional electronic, and merge its capability into electrochemical applications.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Woo Soo Kim
Jiacheng Wang
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Integrated sensing from multiple wearable devices for activity recognition and dead reckoning

Date created: 
2016-03-09
Abstract: 

Wearable devices are increasingly prevalent in our everyday lives. This thesis examines the potential of combining multiple wearable devices worn on different body locations for fitness activity recognition and inertial dead-reckoning. First, a novel method is presented to classify fitness activities using head-worn sensors, with comparisons to other common worn locations on the body. Using multiclass Support Vector Machine (SVM) on head-worn sensors, high degree of accuracy was obtained for classifying standing, walking, running, ascending/descending stairs and cycling. Next, a complete inertial dead-reckoning system for walking and running using smartwatch and smartglasses is proposed. Head-turn motion can derail the position propagation on a head-worn dead-reckoning system. Using the relative angle rate-of-change between arm swing direction and head yaw, head-turn motion can be detected. The experimental results show that using the proposed head-turn detection algorithm, head-worn dead-reckoning performance can be greatly improved.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Edward Park
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.